class x {
  public static void main(String args[])   {
    System.out.println("x");
  }
}

class x {
  public static void main(String args[])   {
    int i = 1;
    System.out.println(i);
    ok();
  }
  static void ok()   {
    System.out.println("xx");
  }
}
// Result of this program
// 1
// xx

// Testa.java
// Reference from http://www.thaiall.com/class/TestBubbleSort.java
import java.lang.*;
class aaa {
  int elems=0; 
  Comparable ar[] = new Comparable[2];
  public void insert(Comparable value) { 
     ar[elems] = value;
     elems++;
  }  
  public void printresult() {
     System.out.println(ar[0]+"|"+ar[1]);  // 1|2
  }
}
class Testa {
  public static void main(String[] args) {
    aaa arr = new aaa();
    arr.insert(new Integer(1));
    arr.insert(new Integer(2));
    arr.printresult();
  }
}

// Testb.java
// Reference from http://www.thaiall.com/class/TestBubbleSort.java
import java.lang.*;
class Testb {
  static int elems=0; 
  static Comparable ar[] = new Comparable[2];
  public static void main(String[] args) {
    insert(new Integer(1));
    insert(new Integer(2));
    printresult();
  }
  static void insert(Comparable value) { 
     ar[elems] = value;
     elems++;
  }  
  static void printresult() {
     System.out.println(ar[0]+"|"+ar[1]);  // 1|2
  }
}

class xxx { 
  void prtxx() { 
    System.out.println("xx"); 
  } 
} 
class x { 
  public static void main(String args[]) { 
    System.out.println("x"); 
    new xxx().prtxx(); 
    xxx a = new xxx();  // ไม่มี constructor ใน xxx
    a.prtxx(); 
  } 
} 
// Result of this program
// x
// xx 
// xx

class xxx { 
  void prtxx() { 
    System.out.println("xx"); 
  } 
  xxx() {
    System.out.println("ddd"); 
  }
} 
class x { 
  public static void main(String args[]) { 
    System.out.println("x"); 
    new xxx().prtxx();  // ทำงานทั้ง object และ constructor
    xxx a = new xxx();  // ทำงานเฉพาะ constructor
    a.prtxx();          // ทำงานเฉพาะ object
    new xxx();          // ทำงานเฉพาะ constructor
  } 
} 
// Result of this program
// x
// ddd 
// xx 
// ddd
// xx
// ddd

// x.java
class x { 
  public static void main(String args[]) { 
    subx(); 
  } 
  static void subx() { 
    System.out.println("hen"); 
  } 
} 

// y.java
class y { 
  public static void main(String args[]) { 
    System.out.println("rat"); 
    x a = new x(); 
    a.subx(); 
  } 
}
// Result of this program
// rat
// hen

// x.java
import java.util.*;
import java.lang.*;
class a {
  int b;
  a() {
    p("Call object a");
  }
  a(int i) {
    p("Number is " + i);
  }
  void c() {
    p("Receive nothing");
  }
  void c(int i) {
    p("Number = " + i);
  }
  void c(String d) {
    p("Word = " + d);
  }
  static void p(String s) {
    System.out.println(s);
  }
}
class x {
  public static void main(String args[]) {
    a n = new a(2);
    n.c();
    n.c(3);
    n.c("This is test");
    new a();
  }
}
// Result of this program
// Number is 2
// Receive nothing
// Number = 3
// Word = This is test
// Call object a

// a1.java : รุ่นปู่ กำหนดค่า แล้วพิมพ์ 2 บรรทัด
class a1 {   
  static int i;
  public static void main(String args[]) { 
    seti();
    printnumber(i); 
    printline(); 
  } 
  static void seti() { 
    i = 1; 
  } 
  static void printnumber(int j) { 
    System.out.println("Number = " + j); 
  } 
  static void printline() { 
    System.out.println("=========="); 
  } 
} 

// a2.java : รุ่นพ่อ กำหนดค่า i เอง ไม่ใช้ seti() และไม่พิมพ์เส้น
public class a2 extends a1 {
  static int i = 2;
  public static void main (String[] args) {
    printnumber(i); 
  }
}

// a3.java : รุ่นหลาน เปลี่ยนรูปแบบเส้น และไม่ใช้ i จากรุ่นก่อน
public class a3 extends a2 {
  public static void main(String args[]) { 
    printnumber(3); 
    printline(); 
  } 
  static void printline() { 
    System.out.println("----------"); 
  } 
}

// a4.java : รุ่นเหลน แก้ seti ให้ return type ไม่ได้ 
public class a4 extends a3 {
  public static void main(String args[]) { 
    seti();
    printnumber(i); 
    printline(); 
  } 
  static void seti() { 
    // override หรือสืบทอดเปลี่ยนได้เฉพาะ code  
    i = setinew(); 
  } 
  static int setinew() {     
    i = 4; 
    return i;
  } 
}

// a.java 
public class a {
  a() {
    System.out.println("a constructor");
  }
}

// b.java
public class b extends a {
  b(int i) {
    System.out.println("b constructor " + i);
  }
  public static void main (String[] args) {
    b xxx = new b(100);
  }
}
// Result of this program
// a constructor
// b constructor 100

// a.java is superclass
public class a {
  a() {
    System.out.println("a constructor");
  }
  void aa() {
    System.out.println("aa in class a");
  }
}

// b.java is superclass of c.java and subclass of a.java
public class b extends a {
  b() {
    System.out.println("b constructor");
  }
  void aa() {
    System.out.println("aa in class b");
  }
}

// c.java is subclass of b.java
public class c extends b {
  c() {
    System.out.println("c constructor ");
  }
  void aa() {
    System.out.println("aa in class c");
    super.aa(); // call aa in superclass
    new a().aa();
  }
  public static void main(String args[]) { 
    c d = new c();
    d.aa();
    // aa(); can not run because aa should be static
    new a().aa();
  } 
}
// Result of this program
// a constructor
// b constructor
// c constructor
// aa in class c
// aa in class b
// a constructor
// aa in class a
// a constructor
// aa in class a

// a.java
class a {
  a() {
    System.out.println("a constructor");
  }
}

// b.java
public class b {
  public a aa =  new a(); 
  public static void main (String args[]) {
    b x = new b();
  }
  b() {
    System.out.println("b constructor");
  }
}
// Result of this program
// a constructor
// b constructor

// a.java
class a {
  a() {
    System.out.println("a constructor");
  }
}

// b.java
public class b {
  public a aa; 
  public static void main (String args[]) {
    b x = new b();
  }
  b() {
    System.out.println("b constructor");
    new a();
  }
}
// Result of this program
// b constructor
// a constructor

// ========================
// Technique of composition
// ========================
// wheel.java
class wheel {
  private int a;
  private int b;
  public car thecar;
  wheel() {
    System.out.println("constructor wheel() from class wheel");
  }
  public void putwheel() {
    System.out.println("putwheel() from class wheel");
  }
}

// เมื่อแปล door จะแปล car ด้วย
// door.java
class door {
  private int x;
  private int y;
  public car thecar;
  door() {
    System.out.println("constructor door() from class door");
  }
  public void putdoor() {
    System.out.println("cleandoor() from class door");
  }
}

// แปล car จะแปล และได้ wheel.class และ door.class
// car.java
public class car {
  public wheel thewheel =  new wheel();
  public door thedoor =  new door();
  public static void main (String args[]) {
    car  x = new car();
    x.thewheel.putwheel();
    x.thedoor.putdoor();
  }
  car() {
    System.out.println("Constructor car()");
  }
  public void drive() {
    System.out.println("drive()");
  }
}
// Result of this program
// constructor wheel() from class wheel
// constructor door() from class door
// Constructor car()
// putwheel() from class wheel
// cleandoor() from class door